org.grouplens.grapht.solver

Class DependencySolver

java.lang.Object

org.grouplens.grapht.solver.DependencySolver

public class DependencySolver
extends Object

DependencySolver is a utility for resolving Desires into a dependency graph, where nodes are shared when permitted by a Satisfaction's dependency configuration. It supports qualified and context-aware injection, and just-in-time injection if the type has an injectable constructor.

The conceptual binding function used by this solver is represented as a list of prioritized functions. Functions at the start of the list are used first, which makes it easy to provide custom functions that override default behaviors.

This solver does not support cyclic dependencies because of the possibility that a context later on might activate a bind rule that breaks the cycle. To ensure termination, it has a maximum context depth that is configurable.

Author:

GroupLens Research

See Also:

DefaultInjector

Field Summary

Fields

Modifier and Type	Field and Description
static Component	ROOT_SATISFACTION

Method Summary

Modifier and Type	Method and Description
DAGNode<Component,Dependency>	getBackEdge(DAGNode<Component,Dependency> parent, Desire desire) Get the back edge for a particular node and desire, if one exists.
com.google.common.collect.SetMultimap<DAGNode<Component,Dependency>,DAGEdge<Component,Dependency>>	getBackEdges() Get the map of back-edges for circular dependencies.
DAGNode<Component,Dependency>	getGraph() Get the current full dependency graph.
DAGNode<Component,Dependency>	getRootNode() Deprecated. Use getGraph() instead.
static InjectionContext	initialContext() Get an initial injection context.
static DependencySolverBuilder	newBuilder() Create a new dependency solver builder.
void	resolve(Desire desire) Update the dependency graph to include the given desire.
DAGNode<Component,Dependency>	rewrite(DAGNode<Component,Dependency> graph) Rewrite a dependency graph using the rules in this solver.
static DAGNode<Component,Dependency>	rootNode() Get a singleton root node for a dependency graph.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ROOT_SATISFACTION

public static final Component ROOT_SATISFACTION

Method Detail

initialContext

public static InjectionContext initialContext()

Get an initial injection context.

Returns:

The context from the initial injection.

rootNode

public static DAGNode<Component,Dependency> rootNode()

Get a singleton root node for a dependency graph.

Returns:

A root node for a dependency graph with no resolved objects.

newBuilder

public static DependencySolverBuilder newBuilder()

Create a new dependency solver builder.

Returns:

A dependency solver builder.

getGraph

public DAGNode<Component,Dependency> getGraph()

Get the current full dependency graph. This consists of a synthetic root node with edges to the resolutions of all dependencies passed to resolve(Desire).

Returns:

The resolved dependency graph.

getBackEdges

public com.google.common.collect.SetMultimap<DAGNode<Component,Dependency>,DAGEdge<Component,Dependency>> getBackEdges()

Get the map of back-edges for circular dependencies. Circular dependencies are only allowed via provider injection, and only if ProviderBindingFunction is one of the binding functions. In such cases, there will be a back edge from the provider node to the actual node being provided, and this map will report that edge.

Returns:

A snapshot of the map of back-edges. This snapshot is entirely independent of the back edge map maintained by the dependency solver.

getBackEdge

public DAGNode<Component,Dependency> getBackEdge(DAGNode<Component,Dependency> parent,
                                                 Desire desire)

Get the back edge for a particular node and desire, if one exists.

Returns:

The back edge, or null if no edge exists.

See Also:

getBackEdges()

getRootNode

@Deprecated
public DAGNode<Component,Dependency> getRootNode()

Deprecated. Use getGraph() instead.

Get the root node.

resolve

public void resolve(Desire desire)
             throws ResolutionException

Update the dependency graph to include the given desire. An edge from the root node to the desire's resolved satisfaction will exist after this is finished.

Parameters:

desire - The desire to include in the graph

Throws:

ResolutionException

rewrite

public DAGNode<Component,Dependency> rewrite(DAGNode<Component,Dependency> graph)
                                      throws ResolutionException

Rewrite a dependency graph using the rules in this solver. The accumulated global graph and back edges are ignored and not modified.

Graph rewrite walks the graph, looking for nodes to rewrite. If the desire that leads to a node is matched by a trigger binding function, then it is resolved using the binding functions and replaced with the resulting (merged) node. Rewriting proceeds from the root down, but does not consider the children of nodes generated by the rewriting process.

Parameters:

graph - The graph to rewrite.

Returns:

A rewritten version of the graph.

Throws:

ResolutionException